Image pickup apparatus having iris member and filter units

ABSTRACT

An image pickup apparatus capable of preventing a decline of resolution of a still image while keeping a dynamic range of exposure control. The image pickup apparatus capable of photographing with changing over a moving image and a still image, includes an iris mechanism for changing an amount of light input to an image pickup element by changing an aperture diameter, a filter unit, having a single density or a plurality of densities, for changing the amount of the light input to the image pickup element by its advancing towards and withdrawing from the aperture diameter of the iris mechanism, a unit for driving the iris mechanism and the filter unit independently, and a control unit for setting the filter unit in one of two types of states such as fully covering the aperture diameter of the iris mechanism and fully withdrawing from the aperture diameter in the still image photography.

The present application is a continuation of application of Ser. No.10/632,958, filed Aug. 4, 2003, pending.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image pickup apparatus having aniris member and filter units.

2. Related Background Art

The following is an example of a conventional technology in thiscategory of field.

FIG. 8 is a block diagram showing a configuration of a conventionalimage pickup apparatus.

Referring to FIG. 8, there are shown a lens 1 for forming an image of anobject, an iris mechanism 2 for controlling an amount of incident light,an iris driving motor 3 for driving (moving) the iris mechanism 2, aniris mechanism drive device for driving the iris driving motor 3, aniris state detecting device for detecting a state of the iris mechanism2, an ND filter 6 for controlling the amount of the incident light, anND driving motor 7 for driving the ND filter 6, an ND mechanism drivedevice 8 for driving the ND driving motor 7, and an ND state detectiondevice 9 for detecting a state of the ND mechanism (filter) unit 6.

There are further shown a CCD (Charge-Coupled Device) 10 for performinga photoelectric conversion of the incident light, an image pickupelement drive device 11 for controlling the CCD 10 to readphotoelectrically converted signals and controlling a signalaccumulation time, i.e., controlling a so-called electronic shutterfunction, a CDS/AGC 12 for sampling the photoelectrically convertedsignals and electrically amplifying the signals, an analog-to-digitalconverter (which will be hereinafter be abbreviated to an A/D converter)13 for converting an analog signal as an output of the CDS/AGC 12 into adigital signal, a signal processing device (which will hereinafter becalled a DSP) 14 having a control function of executing processing suchas a color separation, a color difference matrix, etc. after a gammacorrection and thereafter generating standard TV signals by addingsynchronous signals, a memory 15 for storing an image processed by DSP14, a recording medium 16 capable of recording still images and imageinformation thereof, a microcomputer 17 for issuing processing commandsto the DSP 14, and a liquid crystal panel 18 for displaying the image.

Next, a method of controlling the iris mechanism 2 and the ND filter 6will be discussed.

The light incident on the lens 1 travels through the iris mechanism 2and the ND filter 6, and the light restricted by these optical elementsenters the CCD 10. Signals photoelectrically converted by the CCD 10 areconverted into the digital signals by the A/D converter 13 cooperatingwith the CDS/AGC 12 and are objected to camera-signal-processing in theDSP 14. The DSP 14 transmits luminance data corresponding to an exposurecontrol frame to the microcomputer 17, wherein a calculation for theexposure control is made based on the luminance data. If a result ofthis calculation is not proper to the exposure, the iris mechanism 2,the ND filter 6, the electronic shutter and the AGC are controlled sothat the calculation result becomes proper.

Among these four exposure control parameters, a control relationshipbetween the iris mechanism 2 and the ND filter 6 will be explained. Tostart with, when controlling the exposure in such a direction as toreduce the incident light from a state where the iris mechanism 2remains open and the ND filter 6 entirely withdraws from an aperturediameter of the iris mechanism 2, the iris mechanism 2 closes up (stopsdown) to a certain aperture diameter, and, after this aperture diameterof the iris mechanism 2 has been fixed, the ND filter 6 is consecutivelyadvanced stepwise, thereby controlling the exposure with the ND filter 6(see FIGS. 9A to 9E).

What has been required of the exposure/control of the conventional imagepickup apparatus is given as follows. This will be explained referringto FIGS. 9A to 9E.

Under the conventional exposure control, as shown in FIG. 9B, the NDfilter 6 is advanced halfway such as only by a half-insertion towardsthe aperture of the iris mechanism and, as shown in FIGS. 9C and 9D,different-density areas of the ND filter 6 dually cover the aperturediameter of the iris mechanism 2.

As described above, if the ND filter 6 is advanced halfway towards theaperture diameter of the iris mechanism 2 or the different-density areasof the ND filter 6 cover the aperture diameter, there arises a problemin which an image resolution declines due to an occurrence ofdiffraction of the light that is caused by level differences both inthickness and in density of the ND filter 6. Therefore, the ND filter 6cannot be inserted for still image photography that gives the priorityto the image resolution so that a dynamic range of the exposure controldecreases to an extent corresponding to a density of the ND filter 6 ascompared with the moving image photography.

SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to providean image pickup apparatus capable of preventing a decline of aresolution of a still image while keeping a dynamic range of exposurecontrol.

According to the present invention, the foregoing object is attained byproviding an image pick apparatus capable of photographing with changingover a first mode for recording a plurality of frames and a second modefor recording one frame in accordance with a predetermined action,comprising an iris mechanism for changing an amount of light with whichan image pickup element is irradiated, a filter unit for changing theamount of the light input, and a driving unit for driving the irismechanism and the filter unit independently, wherein the driving unitdrives the filter unit in different manners between the first mode andthe second mode.

In one aspect of the present invention, an image pick apparatus capableof photographing with changing over a first mode for recording aplurality of frames and a second mode for recording one frame inaccordance with a predetermined action, comprises an iris mechanism forchanging an amount of light with which an image pickup element isirradiated, by changing an aperture diameter, a filter unit having asingle density or a plurality of densities, for changing an amount ofincident light, a unit for driving the iris mechanism and the filterunit independently, and a control unit for setting, in the second mode,the filter unit in one of states of covering an aperture diameter of theiris mechanism and of withdrawing from the aperture diameter of the irismechanism.

In one aspect of the present invention, an image pick apparatus capableof photographing with changing over a first mode for recording aplurality of frames and a second mode for recording one frame inaccordance with a predetermined action, comprising an iris mechanism forchanging an amount of light with which an image pickup element isirradiated, by changing an aperture diameter, a filter unit, having aplurality of densities, for changing an amount of light input, a unitfor driving the iris mechanism and the filter unit independently, and acontrol unit for performing drive control of the filter unit so that thefilter unit is driven from the state in which a first density area ofthe filter unit is withdrawn from the aperture diameter of the irismechanism to a state in which the first density area of the filter unitcovers the aperture diameter when the aperture diameter of the irismechanism is changed so as to be opened in the second mode and theaperture diameter reaches a predetermined aperture diameter.

In one aspect of the present invention, an image pick apparatus capableof photographing with changing over a first mode for recording aplurality of frames and a second mode for recording one frame inaccordance with a predetermined action, comprising an iris mechanism forchanging an amount of light with which an image pickup element isirradiated, by changing an aperture diameter, a filter unit, having aplurality of densities, for changing an amount of incident light, a unitfor driving the iris mechanism and the filter unit independently, and acontrol unit for performing drive control of the filter unit so that thefilter unit is driven from the state in which a first density area ofthe filter unit covers the aperture diameter of the iris mechanism to astate in which the first density area of the filter unit is withdrawnfrom the aperture diameter when the aperture diameter of the irismechanism is driven so as to be closed up in the second mode and theaperture diameter reaches a predetermined aperture diameter.

In one aspect of the present invention, an image pickup apparatuscomprising an iris mechanism for changing an amount of light with whichan image pickup element is irradiated, a filter unit for changing theamount of the light, a unit for driving the iris mechanism and thefilter unit independently, an image size changing unit for changing asize of an image to be captured, and a control unit for changing adriving method of the filter unit in accordance with the image size.

In one aspect of the present invention, an image pick apparatus capableof photographing with changing over a first mode for recording aplurality of frames and a second mode for recording one frame inaccordance with a predetermined action, comprising an iris mechanism forchanging an amount of light with which an image pickup element isirradiated, by changing an aperture diameter, a filter unit, having aplurality of densities, for changing an amount of light input, a unitfor driving the iris mechanism and the filter unit independently, animage size changing unit for changing a size of an image to bephotographed in the second mode, and a control unit for consecutivelyinserting or withdrawing the filter unit towards or from the aperturediameter of the iris mechanism in a case where a predetermined imagesize is designated by the image size changing unit.

In another aspect of the present invention, in the image pick apparatus,the control unit performs drive control of the filter unit so that thefilter unit is driven so as to withdraw from the state of covering theaperture diameter when the aperture diameter of the iris mechanism ischanged so as to be closed up in the second mode and the aperturediameter reaches a predetermined aperture diameter.

Other objects and advantages besides those discussed above shall beapparent to those skilled in the art from the description of a preferredembodiment of the invention which follows. In the description, referenceis made to accompanying drawings, which form a part hereof, and whichillustrate an example of the invention, Such example, however, is notexhaustive of the various embodiments of the invention, and thereforereference is made to the claims which follow the description fordetermining the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of an image pickupapparatus in a first embodiment of the present invention;

FIG. 2 is a diagram showing how an exposure is controlled in the firstembodiment;

FIG. 3 is a flowchart showing a drive control method of an ND filter inthe first embodiment;

FIG. 4 is a block diagram showing a configuration of the image pickupapparatus in a second embodiment of the present invention;

FIG. 5 is a diagram showing how the exposure is controlled in the secondembodiment;

FIG. 6 is a block diagram showing a configuration of the image pickupapparatus in a third embodiment of the present invention;

FIGS. 7A and 7B are diagrams showing image sizes in the thirdembodiment;

FIG. 8 is a block diagram showing a configuration of a conventionalimage pickup apparatus; and

FIGS. 9A, 9B, 9C, 9D and 9E are diagrams showing how the exposure iscontrolled in the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will hereinafter be described withthe accompanying drawings.

First Embodiment Whole Configuration of Image Pickup Apparatus

FIG. 1 is a block diagram showing a configuration of an image pickupapparatus in one embodiment of the present invention. The componentsmarked with the same numerals as those in FIG. 8 are component blockshaving the same functions as those in the prior art, and hence theirrepetitive explanations are herein omitted.

A different point of the configuration of the image pickup apparatus inthe first embodiment from that of the prior art shown in FIG. 8, is thata moving image photographing mode and a still image photographing modeare changed over by connecting a moving/still image changeover switch 19to a microcomputer 17.

To start with, for the moving image, an ND filter 6 having a singledensity as in the case of the prior art is consecutively advancedtowards and withdrawn from an aperture diameter of an iris mechanism 2.Herein, when the photographing mode is changed over to the still imagephotographing mode from the moving image photographing mode by themoving/still image changeover switch 19, the microcomputer 17 calculatesan accumulated charge amount EV of an object when changed over. It isdetermined based on the calculated EV value whether the ND filter 6 isfully advanced towards or fully withdrawn from the aperture diameter ofthe iris mechanism 2. Then, the microcomputer 17 controls an ND filterdrive mechanism 8, thereby controlling the ND filter 6. Thereafter, anexposure is controlled under AGC (Automatic Gain Control) by use of theiris mechanism 2 and an electronic shutter, depending on brightness ofthe object.

Exposure Control in First Embodiment

Next, a process from the full-withdrawing of the ND filter 6 from theaperture diameter of the iris mechanism to the full-advancing thereof inthe still image photographing mode, will be described with reference toFIG. 2 showing an exposure control diagram in the first embodiment.

As illustrated in FIG. 2, as the object becomes brighter, the irismechanism 2 closes up (stops down), and the control of the irismechanism 2 is halted just when the aperture diameter comes to F11.Subsequently the control is conducted so that the ND filter 6 fullycovers the aperture diameter of the iris mechanism 2. At this time, theiris mechanism 2 expands (opens) the aperture diameter to an extentcorresponding to a density of the ND filter 6 in order to compensate thelight shielded by the ND filter 6. The light that cannot be completelycompensated by expanding the aperture diameter of the iris mechanism 2,is further compensated by lowering a shutter speed of the electronicshutter. Namely, the incompletely-compensated light is compensated byelongating an accumulation time of accumulating the light on a CCD(Charge-Coupled Device) 10. This compensation control enables an abruptchange in amount of light due to the advancing of the ND filter 6 tobecome inconspicuous.

According to the first embodiment, the ND filter 6 has 5-level lightshielding capabilities. The iris mechanism has 3-level light shieldingcapabilities from F11 up to F4, and difference of two levels between the5-level and the 3-level is compensated by controlling the shutter speedof the electronic shutter by the two levels in the brighter directionfrom 1/250 sec to 1/60 sec. Thereafter, if the brightness of the objectbecomes much higher, the shutter speed of the electronic shutter is sethigher up to 1/250 sec from 1/60 sec, and the aperture diameter of theiris mechanism is closed up (narrowed down) to an aperture diameter ofF11 from an aperture diameter of F4, thus controlling the exposure.

Inversely, an exposure control method of fully withdrawing the ND filter6 from the state where the ND filter 6 has fully been advanced towardsthe aperture diameter of the iris mechanism 2, is that the exposure iscontrolled in a darkening direction of the object as opposed to theaforementioned brightening direction thereof. Namely, in the state wherethe ND filter 6 is fully advanced towards the aperture diameter of theiris mechanism 2, upon reaching such conditions that the shutter speedof the electronic shutter is 1/60 sec, the iris mechanism 2 comes to theaperture diameter of F4 and the microcomputer 17 judges that the objectis dark, the shutter speed of the electronic shutter is set at 1/250sec, and the iris mechanism 2 closes up (stops down) to the aperturediameter of Fit, wherein the ND filter 6 is fully withdrawn from theaperture diameter of the iris mechanism 2. Thereafter, when the objectfurther darkens, the exposure is controlled by the shutter speed of theelectronic shutter and the iris mechanism 2.

Drive Control Method of ND Filter 6 in First Embodiment

Next, a drive control method of the ND filter 6 in the first embodimentwill be discussed with reference to a flowchart in FIG. 3. Note that aprogram based on the flowchart in FIG. 3 is stored on a storage devicewithin the microcomputer 17 and runs on the microcomputer 17, wherebythe following control method can be actualized.

To begin with, it is judged in step S1 whether the mode is the stillimage photographing mode or not. If judged to be the still imagephotographing mode, the processing proceeds to step S2. Whereas if not,the processing is not executed until the mode is judged to be the stillimage photographing mode.

It is judged in step S2 whether the ND filter 6 is now in a state ofbeing advanced or withdrawn. If the ND filter 6 is advanced, theprocessing advances to step S3. Whereas if withdrawn, the processingproceeds to step S5.

When judging in step S2 that the ND filter 6 is advanced, and theprocessing advances to step S3, wherein it is judged whether the iris isopened wider than F4.0. If opened wider than F4.0, the processingproceeds to step S4. Whereas if not opened wider than F4.0, there is await in step S3 till the iris is opened wider than F4.0.

When advancing to step S4, the ND filter 6 is withdrawn, and the irismechanism 2 closes up (stops down) to F11. Thereafter, the processingproceeds to step S6, wherein a proper exposure is attained by changingthe shutter speed.

When judging in step S2 that the ND filter 6 is withdrawn, and theprocessing advances to step S5, wherein it is judged whether the iris isclosed up narrower than F11. If closed up narrower than F11, theprocessing proceeds to step S7. Whereas if not closed up narrower thanFit, there is a wait in step S5 till the iris is closed up narrower thanF11.

When advancing to step S7, the ND filter 6 is advanced, and the irismechanism 2 is opened up to F4.0. Thereafter, the processing proceeds tostep S6, wherein the proper exposure is acquired by changing the shutterspeed.

Thus, the first embodiment, when photographing the still image, adoptsnot the operation of consecutively inserting the ND filter 6 towards theaperture diameter of the iris but the operation of performing thecontrol as to whether the ND filter 6 is fully advanced or withdrawn.Namely, the ND filter 6 is not advanced towards the aperture diameter ofthe iris till the iris mechanism 2 reaches a certain given aperturediameter of the iris, and further, in the case of desiring to reduce anamount of incident light, the ND filter 6 is advanced so as to cover theentire aperture diameter of the iris mechanism 2. Thus, in the stillimage photography, the ND filter 6 is utilized, thereby preventing adecline of an image resolution due to a diffraction of the light thatoccurs when the ND filter 6 is in the state of neither being fullywithdrawn from the aperture diameter of the iris mechanism 2 nor fullycovering the aperture diameter, and further making it possible to ensurethe same dynamic range of the exposure control as the moving image has.

Second Embodiment

FIG. 4 is a block diagram showing a configuration of the image pickupapparatus according to a second embodiment of the present invention, thecomponents marked with the same numerals as those in the block diagram(FIG. 1) in the first embodiment, are component blocks having the samefunctions as those in the first embodiment, and hence their repetitiveexplanations are herein omitted.

A different point of the configuration of the image pickup apparatus inthe second embodiment from that in the first embodiment, is that amulti-density ND filter 21 exhibiting a plurality of densities is usedas a substitute for the single-density ND filter 6.

Next, a process from the state of the full-withdrawing of amulti-density ND filter 21 from the aperture diameter of the irismechanism 2 to the full-advancing thereof in the still imagephotographing mode, will be described with reference to FIG. 5 showingan exposure control diagram in the second embodiment.

As illustrated in FIG. 5, as the object becomes brighter, the irismechanism 2 closes up, the control of the iris mechanism 2 is halted atthe aperture diameter of F11, and subsequently the multi-density NDfilter 21 is controlled so that a highest-density area of themulti-density ND filter 21 covers the entire aperture diameter of theiris mechanism 2.

Then, in order for the iris mechanism 2 to compensate the light shieldedby the multi-density ND filter 21, the aperture diameter of the irismechanism 2 opens (expands) so that different density areas of the NDfilter 21 do not exist at the aperture diameter of the iris mechanism 2.At this time, the light that can not be completely compensated byexpanding the aperture diameter of the iris mechanism 2, is furthercompensated by lowering the shutter speed of the electronic shutter inthe same way as the first embodiment takes.

In the second embodiment, the multi-density ND filter 21 has the 5-levellight shielding capabilities. The iris mechanism 2 has 3-level lightshielding capabilities from F11 up to F4, and hence difference of twolevels between the 5-level and the 3-level is compensated by controllingthe shutter speed of the electronic shutter by the two levels from 1/250sec to 1/60 sec in the brighter direction. Thereafter, if the brightnessof the object becomes much higher, as in the first embodiment, theshutter speed of the electronic shutter is set higher up to 1/250 secfrom 1/60 sec. and the aperture diameter of the iris mechanism narrowsdown to an aperture diameter of F11 from an aperture diameter of F4,thus controlling the exposure.

Inversely, an exposure control method of fully withdrawing themulti-density ND filter 21 from the state where the multi-density filter21 has fully been advanced towards the aperture diameter of the irismechanism 2, is that the exposure is controlled in the darkeningdirection of the object as opposed to the aforementioned brighteningdirection of the object.

As discussed above, the second embodiment, in the still imagephotography of the image pickup apparatus incorporating the ND filter 21having the plurality of densities, adopts not the operation ofconsecutively inserting the ND filter 21 towards the aperture diameterof the iris but the operation of performing the control as to whetherthe ND filter 21 is fully advanced or withdrawn. Namely, the ND filter21 is not advanced towards the aperture diameter of the iris till theiris mechanism 2 reaches a certain given aperture diameter of the iris,and further, in the case of desiring to reduce an amount of incidentlight, the ND filter 21 is advanced so as to cover the entire aperturediameter of the iris mechanism 2 with the single-density area of the NDfilter 21. Thus, in the still image photography, the ND filter 21 isutilized, thereby preventing the decline of the image resolution due tothe diffraction of the light that occurs when the ND filter 21 is in thestate of neither being fully withdrawn from the aperture diameter of theiris mechanism 2 nor fully covering the aperture diameter, and due tothe diffraction of the light that occurs when the ND filter 21 is in astate of fully covering the aperture diameter of the iris mechanism 21with a different-density-mixed area of the ND filter 21, and furthermaking it possible to ensure the same dynamic range of the exposurecontrol as the moving image has.

Third Embodiment

FIG. 6 is a block diagram showing a configuration of the image pickupapparatus according to a third embodiment of the present invention, thecomponents marked with the same numerals as those in the block diagram(FIG. 8) in the prior art, are component blocks having the samefunctions as those in the prior art, and hence their repetitiveexplanations are herein omitted.

A different point of the configuration of the image pickup apparatus inthe third embodiment from that in the prior art illustrated in FIG. 8,is that a still image size change switch 20 connected to themicrocomputer 17 changes an image size of the still image.

At first, when the still image size change switch 20 selects acomparatively small still image size (e.g., 640×480 pixels: see FIG. 7A)exhibiting a low resolution, as in the prior art, the ND filter 6 isconsecutively advanced towards or withdrawn from the aperture diameterof the iris mechanism 2.

Herein, the change switch 20, upon a changeover from a low resolutionmode to a high resolution mode, selects a comparatively large stillimage size (e.g., 1,280×960 pixels: see FIG. 7B) as an image size. Then,the microcomputer 17 calculates an accumulated charge amount EV of theobject when changed over, thereby determining based on the thuscalculated EV value whether the ND filter 6 is fully advanced towards orfully withdrawn from the aperture diameter of the iris mechanism 2.Then, the microcomputer 17 controls the ND filter 6 by controlling thedrive mechanism 8 for the ND filter 6. Thereafter, the exposure iscontrolled under the AGC by use of the iris mechanism 2 and theelectronic shutter, depending on the brightness of the object.

Note that the third embodiment has exemplified the single-density NDfilter 6 and may also take the configuration involving the use of themulti-density ND filter 21 as exemplified in the second embodiment. Inthe high resolution mode, the processing from the state where the NDfilter 6 and the multi-density ND filter 21 are fully withdrawn from theaperture diameter of the iris mechanism 2 to the full advancing thereoftowards aperture diameter, or the processing from the state where the NDfilter 6 and the multi-density ND filter 21 are fully advanced towardsthe aperture diameter of the iris mechanism 2 to the full-withdrawingthereof, are the same as those in the first embodiment and the secondembodiment.

Thus, the image pickup apparatus according to the third embodiment hasthe mode in which the image exhibiting the high-quality though the imagerecording size becomes comparatively large can be captured in the stillimage photography, and also has the image size changeover functioncapable of reducing the image size though the image quality becomes low.This image pickup apparatus takes the control method of controlling theND filter 6 in the two ways of advancing and withdrawing the ND filter 6as described above when selecting the high-quality image photographygiven a priority of the image-quality, and when selecting thelow-quality image photography given a priority of the image size,changes the control method to that of consecutively the ND filter 6 inthe same manner as in the moving image photography. With this changeoverof the control methods, the exposure can be controlled smoothly with noabrupt change in luminance in the low-quality image photography, and thedecline of the resolution of the still image can be prevented in a waythat does not narrow the dynamic range of the exposure control in thehigh-quality image photography.

The present invention may be, without being limited to the apparatusesin the embodiments discussed above, applied to a system configured by aplurality of appliances and also to an apparatus constructed of onesingle appliance. The present invention is, as a matter of course,accomplished by supplying the system or the apparatus with a storagemedium stored with software program codes for actualizing the functionsin the embodiments discussed above, and making a computer (or a CPU andan MPU) of the system or the apparatus read and execute the programcodes stored on the storage medium.

In this case, it follows that the program codes themselves, which havebeen read from the storage medium, actualize the functions in theembodiments discussed above, and that the storage medium stored with theprogram codes configures the present invention. The storage medium forsupplying the program codes may involve using, for example, a floppy(registered trademark) disk, a hard disk, an optical disk, amagneto-optic disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatilememory card and a ROM. In addition to the case where the computerexecutes the readout program codes and the functions in the embodimentsdiscussed above are thereby actualized, the present invention, needlessto say, further includes a case in which the OS, etc. running on thecomputer executes a part or the whole of the actual processing on thebasis of the instructions of the program codes, and the functions in theembodiments discussed above are actualized by such processing.

Moreover, the program codes read from the storage medium are written toa memory provided in a function extended board advanced into thecomputer and in a function extended unit connected to the computer,thereafter a CPU, etc. provided in the extended board or the extendedunit executes processing of these extended functions on the basis of thesubsequent instructions of the next program codes and thus executes apart or the whole of the actual processing, and the functions in theembodiments discussed above are actualized by such processing.

As discussed so far in detail, according to the present invention, themethod of driving the filter unit is changed according to the stillimage photography and the moving image photography, thereby making itpossible to prevent the decline of the resolution of the still image ina way that does not narrow the dynamic range of the exposure control.

Moreover, the filter unit driving method is changed according to thestill image size, and it is therefore feasible to prevent the decline ofthe resolution of the still image in a way that does not narrow thedynamic range of the exposure control in the high-resolution imagephotography and to perform the smooth exposure control in thelow-resolution image photography.

The present invention is not limited to the above embodiment and variouschanges and modifications can be made within the spirit and scope of thepresent invention. Therefore, to apprise the public of the scope of thepresent invention, the following claims are made.

1. An image pickup apparatus including an iris mechanism for changingthe amount of light with which an image pickup element is irradiated bychanging an aperture diameter using the iris mechanism and a filterunit, having a single density, for changing the amount of incidentlight, said image pickup apparatus being capable of switching between afirst mode of photographing for recording a plurality of frames and asecond mode of photographing for recording one frame in accordance witha predetermined action, said image pickup apparatus comprising: acontrol unit configured to control the filter unit so that the filterunit is controlled during photographing in the first mode so as to bepositioned at a plurality of positions including a position at which thefilter unit partially covers the aperture diameter of the irismechanism, and is configured to control the filter unit duringphotographing in the second mode so as not to position the filter unitat a position at which the filter unit partially covers the aperturediameter of the iris mechanism.
 2. A control method of an image pickupapparatus capable of photographing and switching between a first modefor recording a plurality of frames and a second mode for recording oneframe in accordance with a predetermined action, the apparatuscomprising an iris mechanism for changing the amount of light with whichan image pickup element is irradiated by changing an aperture diameterof the iris mechanism, and a filter unit, having a single density, forchanging the amount of light input to the image pickup element byadvancing the filter unit toward and withdrawing the filter unit fromthe aperture diameter, said method comprising: a step of discriminatingwhich of the first mode and the second mode is selected; and a step ofcontrolling the filter unit so that the filter unit is controlled duringphotographing in the first mode so as to be positioned at a plurality ofpositions including a position at which the filter unit partially coversthe aperture diameter of the iris mechanism, and so that the filter unitis controlled during photographing in the second mode so as not to bepositioned at a position at which the filter unit partially covers theaperture of diameter of the iris mechanism.
 3. An image pickup apparatusfor changing the amount of light with which an image pickup element isirradiated by changing an aperture diameter of an iris mechanism andusing a filter unit having a plurality of densities, said image pickupapparatus comprising: a control unit configured to control the filterunit so that the filter unit is controlled during photographing in afirst mode so as to be positioned at a plurality of positions includingat least a position at which the filter unit partially covers theaperture diameter of the iris mechanism, and configured to control thefilter unit during photographing in a second mode so as not to bepositioned at a position at which a first density portion of the filterunit partially covers the aperture diameter of the iris mechanism.
 4. Animage pickup apparatus according to claim 3, wherein said control unitperforms drive control of the filter unit so that the filter unit isdriven from the position at which the filter unit withdraws entirelyfrom the aperture diameter of the iris mechanism to the position atwhich the first density portion of the filter unit covers over all ofthe aperture diameter of the iris mechanism when the aperture diameterof the iris mechanism is changed so as to be opened in the second modeand the aperture diameter reaches a predetermined aperture diameter. 5.An image pickup apparatus according to claim 3, wherein said controlunit performs drive control of the filter unit so that the filter unitis driven from the position at which the filter unit covers over all ofthe aperture diameter of the iris mechanism to the position at which thefirst density portion of the filter unit withdraws entirely from theaperture diameter of the iris mechanism when the aperture diameter ofthe iris mechanism is changed so as to be closed up in the second modeand the aperture diameter reaches a predetermined aperture diameter.